diff options
Diffstat (limited to 'include/linux/rmap.h')
| -rw-r--r-- | include/linux/rmap.h | 289 |
1 files changed, 241 insertions, 48 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 988d176472df..bd3504d11b15 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -11,6 +11,8 @@ #include <linux/rwsem.h> #include <linux/memcontrol.h> #include <linux/highmem.h> +#include <linux/pagemap.h> +#include <linux/memremap.h> /* * The anon_vma heads a list of private "related" vmas, to scan if @@ -39,12 +41,15 @@ struct anon_vma { atomic_t refcount; /* - * Count of child anon_vmas and VMAs which points to this anon_vma. + * Count of child anon_vmas. Equals to the count of all anon_vmas that + * have ->parent pointing to this one, including itself. * * This counter is used for making decision about reusing anon_vma * instead of forking new one. See comments in function anon_vma_clone. */ - unsigned degree; + unsigned long num_children; + /* Count of VMAs whose ->anon_vma pointer points to this object. */ + unsigned long num_active_vmas; struct anon_vma *parent; /* Parent of this anon_vma */ @@ -77,7 +82,7 @@ struct anon_vma { struct anon_vma_chain { struct vm_area_struct *vma; struct anon_vma *anon_vma; - struct list_head same_vma; /* locked by mmap_sem & page_table_lock */ + struct list_head same_vma; /* locked by mmap_lock & page_table_lock */ struct rb_node rb; /* locked by anon_vma->rwsem */ unsigned long rb_subtree_last; #ifdef CONFIG_DEBUG_VM_RB @@ -86,19 +91,15 @@ struct anon_vma_chain { }; enum ttu_flags { - TTU_MIGRATION = 0x1, /* migration mode */ - TTU_MUNLOCK = 0x2, /* munlock mode */ - TTU_SPLIT_HUGE_PMD = 0x4, /* split huge PMD if any */ TTU_IGNORE_MLOCK = 0x8, /* ignore mlock */ - TTU_IGNORE_ACCESS = 0x10, /* don't age */ + TTU_SYNC = 0x10, /* avoid racy checks with PVMW_SYNC */ TTU_IGNORE_HWPOISON = 0x20, /* corrupted page is recoverable */ TTU_BATCH_FLUSH = 0x40, /* Batch TLB flushes where possible * and caller guarantees they will * do a final flush if necessary */ TTU_RMAP_LOCKED = 0x80, /* do not grab rmap lock: * caller holds it */ - TTU_SPLIT_FREEZE = 0x100, /* freeze pte under splitting thp */ }; #ifdef CONFIG_MMU @@ -130,6 +131,11 @@ static inline void anon_vma_lock_read(struct anon_vma *anon_vma) down_read(&anon_vma->root->rwsem); } +static inline int anon_vma_trylock_read(struct anon_vma *anon_vma) +{ + return down_read_trylock(&anon_vma->root->rwsem); +} + static inline void anon_vma_unlock_read(struct anon_vma *anon_vma) { up_read(&anon_vma->root->rwsem); @@ -160,50 +166,213 @@ static inline void anon_vma_merge(struct vm_area_struct *vma, unlink_anon_vmas(next); } -struct anon_vma *page_get_anon_vma(struct page *page); +struct anon_vma *folio_get_anon_vma(struct folio *folio); + +/* RMAP flags, currently only relevant for some anon rmap operations. */ +typedef int __bitwise rmap_t; + +/* + * No special request: if the page is a subpage of a compound page, it is + * mapped via a PTE. The mapped (sub)page is possibly shared between processes. + */ +#define RMAP_NONE ((__force rmap_t)0) + +/* The (sub)page is exclusive to a single process. */ +#define RMAP_EXCLUSIVE ((__force rmap_t)BIT(0)) -/* bitflags for do_page_add_anon_rmap() */ -#define RMAP_EXCLUSIVE 0x01 -#define RMAP_COMPOUND 0x02 +/* + * The compound page is not mapped via PTEs, but instead via a single PMD and + * should be accounted accordingly. + */ +#define RMAP_COMPOUND ((__force rmap_t)BIT(1)) /* * rmap interfaces called when adding or removing pte of page */ void page_move_anon_rmap(struct page *, struct vm_area_struct *); void page_add_anon_rmap(struct page *, struct vm_area_struct *, - unsigned long, bool); -void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, - unsigned long, int); + unsigned long address, rmap_t flags); void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, - unsigned long, bool); -void page_add_file_rmap(struct page *, bool); -void page_remove_rmap(struct page *, bool); + unsigned long address); +void page_add_file_rmap(struct page *, struct vm_area_struct *, + bool compound); +void page_remove_rmap(struct page *, struct vm_area_struct *, + bool compound); void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, - unsigned long); + unsigned long address, rmap_t flags); void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *, - unsigned long); + unsigned long address); -static inline void page_dup_rmap(struct page *page, bool compound) +static inline void __page_dup_rmap(struct page *page, bool compound) { atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount); } +static inline void page_dup_file_rmap(struct page *page, bool compound) +{ + __page_dup_rmap(page, compound); +} + +/** + * page_try_dup_anon_rmap - try duplicating a mapping of an already mapped + * anonymous page + * @page: the page to duplicate the mapping for + * @compound: the page is mapped as compound or as a small page + * @vma: the source vma + * + * The caller needs to hold the PT lock and the vma->vma_mm->write_protect_seq. + * + * Duplicating the mapping can only fail if the page may be pinned; device + * private pages cannot get pinned and consequently this function cannot fail. + * + * If duplicating the mapping succeeds, the page has to be mapped R/O into + * the parent and the child. It must *not* get mapped writable after this call. + * + * Returns 0 if duplicating the mapping succeeded. Returns -EBUSY otherwise. + */ +static inline int page_try_dup_anon_rmap(struct page *page, bool compound, + struct vm_area_struct *vma) +{ + VM_BUG_ON_PAGE(!PageAnon(page), page); + + /* + * No need to check+clear for already shared pages, including KSM + * pages. + */ + if (!PageAnonExclusive(page)) + goto dup; + + /* + * If this page may have been pinned by the parent process, + * don't allow to duplicate the mapping but instead require to e.g., + * copy the page immediately for the child so that we'll always + * guarantee the pinned page won't be randomly replaced in the + * future on write faults. + */ + if (likely(!is_device_private_page(page) && + unlikely(page_needs_cow_for_dma(vma, page)))) + return -EBUSY; + + ClearPageAnonExclusive(page); + /* + * It's okay to share the anon page between both processes, mapping + * the page R/O into both processes. + */ +dup: + __page_dup_rmap(page, compound); + return 0; +} + +/** + * page_try_share_anon_rmap - try marking an exclusive anonymous page possibly + * shared to prepare for KSM or temporary unmapping + * @page: the exclusive anonymous page to try marking possibly shared + * + * The caller needs to hold the PT lock and has to have the page table entry + * cleared/invalidated. + * + * This is similar to page_try_dup_anon_rmap(), however, not used during fork() + * to duplicate a mapping, but instead to prepare for KSM or temporarily + * unmapping a page (swap, migration) via page_remove_rmap(). + * + * Marking the page shared can only fail if the page may be pinned; device + * private pages cannot get pinned and consequently this function cannot fail. + * + * Returns 0 if marking the page possibly shared succeeded. Returns -EBUSY + * otherwise. + */ +static inline int page_try_share_anon_rmap(struct page *page) +{ + VM_BUG_ON_PAGE(!PageAnon(page) || !PageAnonExclusive(page), page); + + /* device private pages cannot get pinned via GUP. */ + if (unlikely(is_device_private_page(page))) { + ClearPageAnonExclusive(page); + return 0; + } + + /* + * We have to make sure that when we clear PageAnonExclusive, that + * the page is not pinned and that concurrent GUP-fast won't succeed in + * concurrently pinning the page. + * + * Conceptually, PageAnonExclusive clearing consists of: + * (A1) Clear PTE + * (A2) Check if the page is pinned; back off if so. + * (A3) Clear PageAnonExclusive + * (A4) Restore PTE (optional, but certainly not writable) + * + * When clearing PageAnonExclusive, we cannot possibly map the page + * writable again, because anon pages that may be shared must never + * be writable. So in any case, if the PTE was writable it cannot + * be writable anymore afterwards and there would be a PTE change. Only + * if the PTE wasn't writable, there might not be a PTE change. + * + * Conceptually, GUP-fast pinning of an anon page consists of: + * (B1) Read the PTE + * (B2) FOLL_WRITE: check if the PTE is not writable; back off if so. + * (B3) Pin the mapped page + * (B4) Check if the PTE changed by re-reading it; back off if so. + * (B5) If the original PTE is not writable, check if + * PageAnonExclusive is not set; back off if so. + * + * If the PTE was writable, we only have to make sure that GUP-fast + * observes a PTE change and properly backs off. + * + * If the PTE was not writable, we have to make sure that GUP-fast either + * detects a (temporary) PTE change or that PageAnonExclusive is cleared + * and properly backs off. + * + * Consequently, when clearing PageAnonExclusive(), we have to make + * sure that (A1), (A2)/(A3) and (A4) happen in the right memory + * order. In GUP-fast pinning code, we have to make sure that (B3),(B4) + * and (B5) happen in the right memory order. + * + * We assume that there might not be a memory barrier after + * clearing/invalidating the PTE (A1) and before restoring the PTE (A4), + * so we use explicit ones here. + */ + + /* Paired with the memory barrier in try_grab_folio(). */ + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) + smp_mb(); + + if (unlikely(page_maybe_dma_pinned(page))) + return -EBUSY; + ClearPageAnonExclusive(page); + + /* + * This is conceptually a smp_wmb() paired with the smp_rmb() in + * gup_must_unshare(). + */ + if (IS_ENABLED(CONFIG_HAVE_FAST_GUP)) + smp_mb__after_atomic(); + return 0; +} + /* * Called from mm/vmscan.c to handle paging out */ -int page_referenced(struct page *, int is_locked, +int folio_referenced(struct folio *, int is_locked, struct mem_cgroup *memcg, unsigned long *vm_flags); -bool try_to_unmap(struct page *, enum ttu_flags flags); +void try_to_migrate(struct folio *folio, enum ttu_flags flags); +void try_to_unmap(struct folio *, enum ttu_flags flags); + +int make_device_exclusive_range(struct mm_struct *mm, unsigned long start, + unsigned long end, struct page **pages, + void *arg); /* Avoid racy checks */ #define PVMW_SYNC (1 << 0) -/* Look for migarion entries rather than present PTEs */ +/* Look for migration entries rather than present PTEs */ #define PVMW_MIGRATION (1 << 1) struct page_vma_mapped_walk { - struct page *page; + unsigned long pfn; + unsigned long nr_pages; + pgoff_t pgoff; struct vm_area_struct *vma; unsigned long address; pmd_t *pmd; @@ -212,9 +381,30 @@ struct page_vma_mapped_walk { unsigned int flags; }; +#define DEFINE_PAGE_VMA_WALK(name, _page, _vma, _address, _flags) \ + struct page_vma_mapped_walk name = { \ + .pfn = page_to_pfn(_page), \ + .nr_pages = compound_nr(_page), \ + .pgoff = page_to_pgoff(_page), \ + .vma = _vma, \ + .address = _address, \ + .flags = _flags, \ + } + +#define DEFINE_FOLIO_VMA_WALK(name, _folio, _vma, _address, _flags) \ + struct page_vma_mapped_walk name = { \ + .pfn = folio_pfn(_folio), \ + .nr_pages = folio_nr_pages(_folio), \ + .pgoff = folio_pgoff(_folio), \ + .vma = _vma, \ + .address = _address, \ + .flags = _flags, \ + } + static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw) { - if (pvmw->pte) + /* HugeTLB pte is set to the relevant page table entry without pte_mapped. */ + if (pvmw->pte && !is_vm_hugetlb_page(pvmw->vma)) pte_unmap(pvmw->pte); if (pvmw->ptl) spin_unlock(pvmw->ptl); @@ -233,27 +423,21 @@ unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); * * returns the number of cleaned PTEs. */ -int page_mkclean(struct page *); +int folio_mkclean(struct folio *); -/* - * called in munlock()/munmap() path to check for other vmas holding - * the page mlocked. - */ -void try_to_munlock(struct page *); +int pfn_mkclean_range(unsigned long pfn, unsigned long nr_pages, pgoff_t pgoff, + struct vm_area_struct *vma); -void remove_migration_ptes(struct page *old, struct page *new, bool locked); +void remove_migration_ptes(struct folio *src, struct folio *dst, bool locked); -/* - * Called by memory-failure.c to kill processes. - */ -struct anon_vma *page_lock_anon_vma_read(struct page *page); -void page_unlock_anon_vma_read(struct anon_vma *anon_vma); int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); /* * rmap_walk_control: To control rmap traversing for specific needs * * arg: passed to rmap_one() and invalid_vma() + * try_lock: bail out if the rmap lock is contended + * contended: indicate the rmap traversal bailed out due to lock contention * rmap_one: executed on each vma where page is mapped * done: for checking traversing termination condition * anon_lock: for getting anon_lock by optimized way rather than default @@ -261,19 +445,24 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); */ struct rmap_walk_control { void *arg; + bool try_lock; + bool contended; /* * Return false if page table scanning in rmap_walk should be stopped. * Otherwise, return true. */ - bool (*rmap_one)(struct page *page, struct vm_area_struct *vma, + bool (*rmap_one)(struct folio *folio, struct vm_area_struct *vma, unsigned long addr, void *arg); - int (*done)(struct page *page); - struct anon_vma *(*anon_lock)(struct page *page); + int (*done)(struct folio *folio); + struct anon_vma *(*anon_lock)(struct folio *folio, + struct rmap_walk_control *rwc); bool (*invalid_vma)(struct vm_area_struct *vma, void *arg); }; -void rmap_walk(struct page *page, struct rmap_walk_control *rwc); -void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc); +void rmap_walk(struct folio *folio, struct rmap_walk_control *rwc); +void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc); +struct anon_vma *folio_lock_anon_vma_read(struct folio *folio, + struct rmap_walk_control *rwc); #else /* !CONFIG_MMU */ @@ -281,7 +470,7 @@ void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc); #define anon_vma_prepare(vma) (0) #define anon_vma_link(vma) do {} while (0) -static inline int page_referenced(struct page *page, int is_locked, +static inline int folio_referenced(struct folio *folio, int is_locked, struct mem_cgroup *memcg, unsigned long *vm_flags) { @@ -289,14 +478,18 @@ static inline int page_referenced(struct page *page, int is_locked, return 0; } -#define try_to_unmap(page, refs) false +static inline void try_to_unmap(struct folio *folio, enum ttu_flags flags) +{ +} -static inline int page_mkclean(struct page *page) +static inline int folio_mkclean(struct folio *folio) { return 0; } - - #endif /* CONFIG_MMU */ +static inline int page_mkclean(struct page *page) +{ + return folio_mkclean(page_folio(page)); +} #endif /* _LINUX_RMAP_H */ |